The mammalian neurokinins comprise a class of peptide neurotransmitters which are found in the peripheral and central nervous systems. The three principal neurokinins are Substance P(SP), Neurokinin A (NKA) and Neurokinin B (NKB).
There are also N-terminally extended forms of at least NKA. At least three receptor types are known for the three principal neurokinins. Based upon their relative selectivities favoring the neurokinin agonists SP, NKA and NKB, the receptors are classified as neurokinin 1 (NK1), neurokinin 2 (NK2) and neurokinin 3 (NK3) receptors, respectively.
It is now recognized that anxiety, stress, and depression are interrelated conditions (File S E Pharmacol, Biochem & Behavior 54/1:3-12, 1996). Moreover, these complex emotional states cannot be due simply to defects in a single neurotransmitter although 5-HT has been ascribed a principal role (Graeff et al., Pharmacol, Biochem & Behavior 54/1: 129-141, 1996). Substance P(SP) was one of the first neuropeptides to be identified in mammalian brain and it is now accepted that all three tachykinins are found within the CNS (Iversen L L J Psychopharmacol 3/1: 1-6, 1989), particularly in the striatonigral neurons, hypothalamus and limbic forebrain (ibid). NK1 and NK3 receptors have been identified in the brain as well (Beaujouan et al., Neurosci. 18: 857-875, 1986). Controversy has existed regarding the presence of the NK2 receptor in brain, although recent evidence shows receptor localization in at least the septal region (Steinberg et al., Eur J Neurosci 10/7:2337-45 1998).
Pharmacological evidence supporting a role for either NK1 or NK2 receptors in anxiety disorders has been accumulating from assorted animal behavioral tests (for examples, see Table 1). Animal models of depression, however, have been used rarely to define the potential utility of NK receptor antagonists. SP stimulates the turnover of other neurotransmitters involved in depression, i.e., 5-HT in the raphe nucleus, an area thought to be linked to depressive phenomena (Forchetti et al., J. Neurochem. 38: 1336-1341, 1982). When injected centrally to nuclei responsible for control of emotion and stress, SP evokes a hemodynamic pressor response bridging this peptide to stress induced hypertension (Ku et al., Peptides; 19/4:677-82, 1998). Moreover, rises in both heart rate and mean arterial blood pressure evoked by physical stress can be blocked in rodents by centrally administered NK1 receptor antagonists (Culman et al., J Pharmacol Exp Ther 280/1:238-46, 1997).
TABLE 1Neurokinin receptor antagonist activity in behavioral tests of anxiety/depression.Cpd (ReceptorAuthortype)Behavioral TestOutcomeTeixeira et al., EurNK1 agonists &Elevated plus-agonists-J PharmacolFK888 (NK1)mazeanxiogenic5;311(1):7-14,SR48968 (NK2)antagonists-1996.anxiolyticFile Pharm Bio BCGP 49823 (NK1)Social interactionanxiolytic58(3): 747-752,1997.Vassout et alCGP 49823 (NK1)Social interactionanxiolyticNeuropeptidestest Elevated plus-inactive26/S1:38, 1994.maze Forced swimantidepressanttest (depression(only at 30 mg/kgmodel)bid)Stratton et al., Eur.GR100679 (NK2)Light-dark boxanxiolyticJ. Pharmacol. 250:SR48968 (NK2)R11-12, 1993.Walsh et al.,GR159897 (NK2)Light-dark boxanxiolyticPsychopharmacologySR48968 (NK2)Marmoset humananxiolytic121:186-191,intruder1995.Description
This invention relates to diaminopropyl compounds; methods of using the compounds in the treatment of disease, the use of the compounds in the manufacture of a medicament; and to pharmaceutical compositions containing such compounds. These compounds antagonize the pharmacological actions of the neurokinin 1 (NK1) receptor. These compounds are useful whenever such antagonism is desired. Thus, such compounds are of value in the treatment of those diseases in which Substance P is implicated, for example, in the treatment of major depressive disorder, severe anxiety disorders, stress disorders, major depressive disorder with anxiety, eating disorders, bipolar disorder, substance use disorder, schizophrenic disorders, psychotic disorders, movement disorders, cognitive disorders, depression and/or anxiety, mania or hypomania, aggressive behaviour, obesity, emesis, rheumatoid arthritis, Alzheimer's disease, cancer, oedema, allergic rhinitis, inflammation, pain, gastrointestinal-hypermotility, Huntington's disease, chronic obstructive pulmonary disorder (COPD), hypertension, migraine, bladder hypermotility, or urticaria.
Accordingly, the present invention provides compounds of the general formula 
The compounds of the present invention may possess a number of chiral centers, for example at —CH(Ph-X1,X2)—. The present invention covers all isomers, diastereoisomers and mixtures thereof that antagonize NK1.
The preferred configuration at —CH(Ph-X1,X2)— is shown hereinbelow: 
X1 and X2 are independently hydrogen, methyl or halogen. Preferably, X1 and X2 are independently hydrogen or halogen provided that at least one of X1 or X2 is halogen. Most favourably, X1 and X2 are both chloro. In a preferred aspect Ph-X1,X2 is 3,4-dichlorophenyl.
R1 is H or CH3.
R2 is H, halogen, —OR7 or C1-4alkyl. In a specific embodiment, R2 is —OR7 or C1-4alkyl.
R3 is H, halogen, —OR7 or —CN. In a specific embodiment, R3 is —CN.
R4 is H, halogen, —OR7 or C1-4alkyl. In a specific embodiment, R4 is H or C1-4alkyl.
R5 is H, C1-8alkyl, —C(═O)R9, —C(═O)OR8, —C(═O)N(R6)R8, —S(═O)nR9, cyanoguanidino or C1-4acylguanidino.
R6 is, independently at each instance, H or C1-6alkyl.
R7 is, independently at each instance, C1-6alkyl.
R8 is H, C1-6alkyl substituted by 0, 1 or 2 substituents selected from —OH and —NHR6 or C1-3alkyl substituted by 1, 2, 3 or 4 halogen atoms.
R9 is, independently at each instance, C1-6alkyl substituted by 0, 1 or 2 substituents selected from —OH and —NHR6 or C1-3alkyl substituted by 1, 2, 3 or 4 halogen atoms,
n is 0, 1 or 2.
Another aspect of the invention involves the use of a compound having the general structure wherein R1-R6 and X1 and X2 are as described above—for the manufacture of a medicament for the treatment of a disease selected from major depressive disorder, severe anxiety disorders, stress disorders, major depressive disorder with anxiety, eating disorders, bipolar disorder, substance use disorder, schizophrenic disorders, psychotic disorders, movement disorders, cognitive disorders, depression and/or anxiety, mania or hypomania, aggressive behaviour, obesity, emesis, rheumatoid arthritis, Alzheimer's disease, cancer, oedema, allergic rhinitis, inflammation, pain, gastrointestinal-hypermotility, Huntington's disease, COPD, hypertension, migraine, bladder hypermotility and urticaria.
Another aspect of the invention involves a pharmaceutical composition comprising a therapeutically-effective amount of an NK1 antagonist having the structure: wherein R1-R6 and X1 and X2 are as described above—and a pharmaceutically-acceptable carrier or diluent.
Another aspect of the invention involves a method of treating major depressive disorder, severe anxiety disorders, stress disorders, major depressive disorder with anxiety, eating disorders, bipolar disorder, substance use disorder, schizophrenic disorders, psychotic disorders, movement disorders, cognitive disorders, depression and/or anxiety, mania or hypomania, aggressive behaviour, obesity, emesis, rheumatoid arthritis, Alzheimer's disease, cancer, oedema, allergic rhinitis, inflammation, pain, gastrointestinal-hypermotility, Huntington's disease, COPD, hypertension, migraine, bladder hypermotility, or urticaria comprising administering an effective amount of an NK1 antagonist having the structure: wherein R1-R6 and X1 and X2 are as described above.
Particular compounds of this invention are provided as the Examples hereinbelow.
CY-Zalkyl, unless otherwise specified, means an alkyl chain containing a minimum Y total carbon atoms and a maximum Z total carbon atoms. These alkyl chains may be branched or unbranched, cyclic, acyclic or a combination of cyclic and acyclic. For example, the following substituents would be included in the general description “C4-7alkyl”: 
Pharmaceutically-acceptable salts may be prepared from the corresponding acid in conventional manner. Non-pharmaceutically-acceptable salts may be useful as intermediates and as such are another aspect of the present invention.
The term “oxo” means a double bonded oxygen (═O).
Some of the compounds of the present invention are capable of forming salts with various inorganic and organic acids and bases and such salts are also within the scope of this invention. Examples of such acid addition salts include acetate, adipate, ascorbate, benzoate, benzenesulfonate, bisulfate, butyrate, camphorate, camphorsulfonate, citrate, cyclohexyl sulfamate, ethanesulfonate, fumarate, glutamate, glycolate, hemisulfate, 2-hydroxyethyl-sulfonate, heptanoate, hexanoate, hydrochloride, hydrobromide, hydroiodide, hydroxymaleate, lactate, malate, maleate, methanesulfonate, 2-naphthalenesulfonate, nitrate, oxalate, pamoate, persulfate, phenylacetate, phosphate, picrate, pivalate, propionate, quinate, salicylate, stearate, succinate, sulfamate, sulfanilate, sulfate, tartrate, tosylate (p-toluenesulfonate), and undecanoate. Base salts include ammonium salts, alkali metal salts such as sodium, lithium and potassium salts, alkaline earth metal salts such as aluminum, calcium and magnesium salts, salts with organic bases such as dicyclohexylamine salts, N-methyl-D-glucamine, and salts with amino acids such as arginine, lysine, ornithine, and so forth. Also, basic nitrogen-containing groups may be quaternized with such agents as: lower alkyl halides, such as methyl, ethyl, propyl, and butyl halides; dialkyl sulfates like dimethyl, diethyl, dibutyl; diamyl sulfates; long chain halides such as decyl, lauryl, myristyl and stearyl halides; aralkyl halides like benzyl bromide and others. Non-toxic physiologically-acceptable salts are preferred, although other salts are also useful, such as in isolating or purifying the product.
The salts may be formed by conventional means, such as by reacting the free base form of the product with one or more equivalents of the appropriate acid in a solvent or medium in which the salt is insoluble, or in a solvent such as water, which is removed in vacuo or by freeze drying or by exchanging the anions of an existing salt for another anion on a suitable ion-exchange resin.
In order to use a compound of the formula (I) or a pharmaceutically acceptable salt thereof for the therapeutic treatment (including prophylactic treatment) of mammals including humans, it is normally formulated in accordance with standard pharmaceutical practice as a pharmaceutical composition.
Therefore in another aspect the present invention provides a pharmaceutical composition which comprises a compound of the formula (I) or a pharmaceutically acceptable salt and pharmaceutically acceptable carrier.
The pharmaceutical compositions of this invention may be administered in standard manner for the disease condition that it is desired to treat, for example by oral, topical, parenteral, buccal, nasal, vaginal or rectal administration or by inhalation or insufflation. For these purposes the compounds of this invention may be formulated by means known in the art into the form of, for example, tablets, capsules, aqueous or oily solutions, suspensions, emulsions, creams, ointments, gels, nasal sprays, suppositories, finely divided powders or aerosols or nebulisers for inhalation, and for parenteral use (including intravenous, intramuscular or infusion) sterile aqueous or oily solutions or suspensions or sterile emulsions.
In addition to the compounds of the present invention the pharmaceutical composition of this invention may also contain, or be co-administered (simultaneously or sequentially) with, one or more pharmacological agents of value in treating one or more disease conditions referred to herein.
The pharmaceutical compositions of this invention will normally be administered to humans so that, for example, a daily dose of 0.01 to 25 mg/kg body weight (and preferably of 0.1 to 5 mg/kg body weight) is received. This daily dose may be given in divided doses as necessary, the precise amount of the compound received and the route of administration depending on the weight, age and sex of the patient being treated and on the particular disease condition being treated according to principles known in the art.
Typically unit dosage forms will contain about 1 mg to 500 mg of a compound of this invention. For example a tablet or capsule for oral administration may conveniently contain up to 250 mg (and typically 5 to 100 mg) of a compound of the formula (I) or a pharmaceutically acceptable salt thereof. In another example, for administration by inhalation, a compound of the formula (I) or a pharmaceutically acceptable salt thereof may be administered in a daily dosage range of 5 to 100 mg, in a single dose or divided into two to four daily doses. In a flirter example, for administration by intravenous or intramuscular injection or infusion, a sterile solution or suspension containing up to 10% w/w (and typically 0.5% w/w) of a compound of the formula (I) or a pharmaceutically acceptable salt thereof may be used.
Therefore in a further aspect, the present invention provides a compound of the formula (I) or a pharmaceutically acceptable salt thereof for use in a method of therapeutic treatment of the human or animal body.
In yet a further aspect the present invention provides a method of treating a disease condition wherein antagonism of the NK1 receptor is beneficial which comprises administering to a warm-blooded animal an effective amount of a compound of the formula (I) or a pharmaceutically-acceptable salt thereof. The present invention also provides the use of a compound of the formula (I) or a pharmaceutically acceptable salt thereof in the preparation of a medicament for use in a disease condition wherein antagonism of the NK1 receptor is beneficial.
The compounds of the formula (I) and their pharmaceutically acceptable salts may be made by processes as described and exemplified herein and by processes similar thereto and by processes known in the chemical art. If not commercially available, starting materials for these processes may be made by procedures which are selected from the chemical art using techniques which are similar or analogous to the synthesis of known compounds.
It is well known in the art how to prepare optically-active forms (for example, by resolution of the racemic form or by synthesis from optically-active starting materials) and how to determine the NK1 antagonist properties by the standard tests known in the art and those described hereinafter.
Some individual compounds within the scope of this invention may contain double bonds. Representations of double bonds in this invention are meant to include both the E and the Z isomer of the double bond. Additionally, some species within the scope of this invention may contain one or more asymmetric centers. This invention includes the use of any of the optically pure stereoisomers as well as any combination of stereoisomers.
In general, compounds bearing a 2-substituted naphthamide can exist as a mixture of conformational isomers (atropisomers); this is believed to result from slow rotation about the naphthalene amide and/or aryl bonds (“The Chemistry of Rotational Isomers”; Oki, M.; Springer Verlag, NY; 1993). Where individual atropisomers have been isolatable, distinct chemical and biological properties have been observed. The compounds of this invention comprise both mixtures of, and individual, atropisomers.
The following biological test methods, data and Examples serve to illustrate and further describe the invention.
The utility of a compound of the invention or a pharmaceutically acceptable salt thereof (hereinafter, collectively referred to as a “compound”) may be demonstrated by standard tests and clinical studies, including those disclosed in the publications described below.
SP Receptor Binding Assay (Test A)
The ability of a compound of the invention to antagonize the binding of SP at the NK1 receptor may be demonstrated using an assay using the human NK1 receptor expressed in Mouse Erythroleukemia (MEL) cells. The human NK1 receptor was isolated and characterized as described in: B. Hopkins, et al. “Isolation and characterization of the human lung NK1 receptor cDNA” Biochem. Biophys. Res. Comm. 1991, 180,1110-1117; and the NK1 receptor was expressed in Mouse Erythroleukemia (MEL) cells using a procedure similar to that described in Test B below.
Neurokinin A (NKA) Receptor Binding Assay (Test B)
The ability of a compound of the invention to antagonize the binding of NKA at the NK2 receptor may be demonstrated using an assay using the human NK2 receptor expressed in Mouse Erythroleukemia (MEL) cells, as described in: Aharony, D., et al. “Isolation and Pharmacological Characterization of a Hampster Neurokinin A Receptor cDNA” Molecular Pharmacology 1994, 45, 9-19.
The selectivity of a compound for binding at the NK1 and the NK2 receptors may be shown by determining its binding at other receptors using standard assays, for example, one using a tritiated derivative of NKB in a tissue preparation selective for NK3 receptors. In general, the compounds of the invention which were tested demonstrated statistically significant binding activity in Test A and Test B with a Ki of 1 mM or much less typically being measured.
Rabbit Pulmonary Artery: NK1 in Vitro Functional Assay (Test C)
The ability of a compound of the invention to antagonize the action of the agonist Ac—[Arg6, Sar9, Met(O2)11] Substance P (6-11), ASMSP, in a pulmonary tissue may be demonstrated as follows.
Male New Zealand white rabbits are euthanized via i.v. injection into the ear vein with 60 mg/kg Nembutal (50 mg/mL). Preceding the Nembutal into the vein is Heparin (1000 units/mL) at 0.0025 mL/kg for anticoagulant purposes. The chest cavity is opened from the top of the rib cage to the sternum and the heart, lungs and part of the trachea are removed. The pulmonary arteries are isolated from the rest of the tissues and cut in half to serve as pairs.
The segments are suspended between stainless steel stirrups, so as not to remove any of the endothelium, and placed in water-jacketed (37.0° C.) tissue baths containing physiological salt solution of the following composition (mM): NaCl, 118.0; KCl, 4.7; CaCl2, 1.8; MgCl2, 0.54; NaH2PO4, 1.0; NaHCO3, 25.0; glucose, 11.0; indomethacin, 0.005 (to inhibit cyclooxygenase); and dl-Propranolol, 0.001(to block β receptors); gassed continuously with 95% O2-5% CO2. Responses are measured on a Grass polygraph via Grass FT-03 transducers.
Initial tension placed on each tissue is 2 grams, which is maintained throughout the 1.0 hour equilibration period. Tissues are washed with the physiological salt solution at 15 minute intervals. At the 30 and 45 minute wash the following treatments are added: 1×10−6 M Thiorphan (to block E.C.3.4-24.11), 3×10−8 M (S)—N—[2-(3,4-dichlorophenyl)-4[4-(2 -oxoperhydropyrimidin-1-yl)piperidino]butyl]-N-methylbenzamide (to block NK2 receptors), and the given concentration of the compound being tested. At the end of the 1.0 h equilibration, 3×10−6 M Phenylephrine hydrochloride is added for 1.0 h. At the end of 1.0 h, a dose relaxation curve to ASMSP is done. Each tissue is treated as a individual and is considered finished when it fails to relax further for 2 consecutive doses. When a tissue is complete, 1×10−3 M Papaverine is added for maximum relaxation.
Percent inhibition is determined when a tested compound produces a statistically significant (p<0.05) reduction of the total relaxation which is calculated using the total relaxation of the Papaverine as 100%. Potencies of the compounds are determined by calculating the apparent dissociation constants (KB) for each concentration tested using the standard equation:KB=[antagonist]/(dose ratio−1)where dose ratio=antilog[(agonist−log molar EC50 without compound)−(−log molar EC50 with compound)]. The KB values may be converted to the negative logarithms and expressed as −log molar KB (i.e. pKB). For this evaluation, complete concentration-response curves for agonist obtained in the absence and presence of the compound tested using paired pulmonary artery rings. The potency of the agonist is determined at 50% of its own maximum relaxation in each curve. The EC50 values are converted to negative logarithms and expressed as −log molar EC50.NK2 In Vitro Functional Assay (Test D)
The ability of a compound of the invention to antagonize the action of the agonist [β-ala8] NKA (4-10), BANK, in a pulmonary tissue may be demonstrated as follows. Male New Zealand white rabbits are euthanized via i.v. injection into the ear vein with 60 mg/kg Nembutal (50 mg/mL). Preceding the Nembutal into the vein is Heparin (1000 units/mL) at 0.0025 mL/kg for anticoagulant purposes. The chest cavity is opened from the top of the rib cage to the sternum and a small incision is made into the heart so that the left and right pulmonary arteries can be cannulated with polyethylene tubing (PE260 and PE190 respectively). The pulmonary arteries are isolated from the rest of the tissues, then rubbed over an intimal surface to remove the endothelium, and cut in half to serve as pairs. The segments are suspended between stainless steel stirrups and placed in water-jacketed (37.0° C.) tissue baths containing physiological salt solution of the following composition (mM): NaCl, 118.0; KCl, 4.7; CaCl2, 1.8; MgCl2, 0.54; NaH2PO4, 1.0; NaHCO3, 25.0; glucose, 11.0; indomethacin, 0.005 (to inhibit cyclooxygenase); gassed continuously with 95% O2-5% CO2. Responses are measured on a Grass polygraph via Grass FT-03 transducers.
Initial tension placed on each tissue is 2 g, which is maintained throughout the 45 min equilibration period. Tissues are washed with the physiological salt solution at 15 min intervals. After the 45 min equilibration period, 3×10−2 M KCl is given for 60 min to test the viability of the tissues. The tissues are then washed extensively for 30 min. The concentration of the compound being tested is then added for 30 min. At the end of the 30 min, a cumulative dose response curve to BANK is performed. Each tissue is treated as a individual and is considered finished when it fails to contract further for 2 consecutive doses. When a tissue is complete, 3×10−2 M BaCl2 is added for maximum contraction.
Percent inhibition is determined when a tested compound produces a statistically significant (p<0.05) reduction of the total contraction which is calculated using the total contraction of the BaCl2 as 100%. Potencies of the compounds are determined by calculating the apparent dissociation constants (KB) for each concentration tested using the standard equation:KB=[antagonist]/(dose ratio−1)where dose ratio=antilog[(agonist−log molar EC50 without compound)−(−log molar EC50 with compound)]. The KB values may be converted to the negative logarithms and expressed as −log molar KB (i.e. pKB). For this evaluation, complete concentration-response curves for agonist obtained in the absence and presence of the compound tested using paired pulmonary artery rings. The potency of the agonist is determined at 50% of its own maximum relaxation in each curve. The EC50 values are converted to negative logarithms and expressed as −log molar EC50.NK1 and NK2 in Vivo Functional Assay (Test E)
The activity of a compound as an antagonist of NK1 and/or NK2 receptors also may be demonstrated in vivo in laboratory animals as described in: Buckner et al. “Differential Blockade by Tachykinin NK1 and NK2 Receptor Antagonists of Bronchoconstriction Induced by Direct-Acting Agonists and the Indirect-Acting Mimetics Capsaicin, Serotonin and 2-Methyl-Serotonin in the Anesthetized Guinea Pig.” J. Pharm. Exp. Ther., 1993, Vol 267(3), pp. 1168-1175. The assay is carried out as follows.
Compounds are tested in anesthetized guinea pigs pretreated with i.v. indomethacin (10 mg/kg, 20 min), propranolol (0.5 mg/kg, 15 min), and thiorphan (10 mg/kg, 10 min).
Antagonists or vehicle are administered i.v. and orally, 30 and 120 min prior to increasing concentrations of agonist, respectively. The agonists used in these studies are ASMSP (Ac-[Arg6,Sar9,Met(O2)11]-SP(6-11)) and BANK (β-ala-8 NKA4-10).
Administered i.v., ASMSP is selective for NK1 receptors, and BANK is selective for NK2 receptors. Maximum response is defined as zero conductance (GL, 1/Rp). ED50 values are calculated (the dose of agonist resulting in a reduction of GL to 50% of baseline), and converted to the negative logarithm (−log ED50). The ED50 values, obtained in the presence (P) and absence (A) of antagonist, are used to calculate a Dose Ratio (P/A), an expression of potency. Data are expressed as mean t SEM and statistical differences were determined using ANOVA/Tukey-Kramer and Student's t-test, with p<0.05 considered statistically significant.
Compounds of the present invention exhibit marked activity in the foregoing tests and are considered useful for the treatment of those diseases in which the NK1 and/or NK2 receptor is implicated, for example, in the treatment of asthma and related conditions.